Glaucoma, a type of optic neuropathy, is a group of eye diseases affecting the retina and optic nerve typically resulting from increases in intraocular pressure (IOP) to above normal for prolonged periods of time. Elevation of TOP can be caused by decreased drainage of the aqueous humor relative to its production. An elevated IOP can cause irreversible damage to the optic nerve and retinal fibers thereby resulting in a permanent loss of vision if left untreated.
The aqueous humor, a clear fluid that fills the anterior segment of the eye (the space between the cornea and lens), is continuously produced by the eye's ciliary body and has many protective functions such as inflating the globe of the eye, providing nutrition for the cornea, trabecular meshwork, lens and anterior vitreous, and protecting against contaminants of the eye. The aqueous humor passes out of the anterior chamber (the space between the cornea and iris) through to the trabecular meshwork and the uveoscleral pathways, both of which contribute to the aqueous humor drainage system.
FIG. 1 is a diagram of the anterior portion of an eye that helps to explain the processes involved in the development of glaucoma. In FIG. 1, representations of the lens 110, cornea 120, iris 130, ciliary body 140, trabecular meshwork 150, and Schlemm's canal 160 are pictured. Aqueous humor fluid is produced by the ciliary body 140 that lies beneath the iris 130 and adjacent to the lens 110 in the anterior segment of the eye. This aqueous humor bathes the lens 110 and iris 130 and flows to the drainage system located at the base of the cornea 120, in the anterior chamber angle, which extends circumferentially around the eye. The trabecular meshwork 150 extends circumferentially around the anterior chamber and is commonly implicated in glaucoma. The trabecular meshwork 150 limits the outflow of aqueous humor and provides a back pressure that directly relates to IOP. Schlemm's canal 160 is located beyond the trabecular meshwork 150 and is fluidically coupled to collector channels allowing aqueous humor to flow out of the anterior chamber. The two arrows in the anterior segment of FIG. 1 show the flow of aqueous humor from the ciliary bodies 140, over the lens 110, over the iris 130, through the trabecular meshwork 150, and into Schlemm's canal 160 and its collector channels.
One method of treating glaucoma includes implanting a drainage device in a patient's eye. The drainage device allows fluid to flow from the interior chamber of the eye to a drainage area, relieving pressure in the eye and thus lowering IOP. At least a portion of these devices are generally held in place by patches and sutures. In some instances, the device is positioned incorrectly or the device moves out of the correct position which leads to injury to the corneal endothelium (i.e., corneal endothelial touch) and/or erosion of the device. Frequently, fluid filled blebs develop at patches and the drainage area. The development of the bleb typically includes fibrosis, which leads to increased flow resistance and it is generally the case that this resistance increases over time. This development and progression of fibrosis reduces or eliminates flow from the anterior chamber, reducing the capacity of the drainage device to affect IOP.
The system and methods disclosed herein overcome one or more of the deficiencies of the prior art.